Style Add New / Edit Post page in WordPress using admin body class. @see http://www.deluxeblogtips.com/?p=1281

admin-body-class.php

<?php
/*
Plugin Name: Admin Body Class Demo
Plugin URI: http://www.deluxeblogtips.com/?p=1281
Description: Style Add New / Edit Post page in WordPress using admin body class
Version: 0.1
Author: Rilwis
Author URI: http://www.deluxeblogtips.com
License: GPL2+
*/

add_action( 'admin_enqueue_scripts', 'rw_add_admin_style' );

/**
 * Enqueue style for admin pages
 * 
 * @return void
 */
function rw_add_admin_style
{
	wp_enqueue_style( 'rw-admin-style', plugins_url( 'admin-style.css', __FILE__ ) );
}

admin-style.css

.post-new-php #titlediv #title,
.post-php #titlediv #title {
    border: 2px solid #f33;
    background: #ff9;
}